The present invention relates to a motor-driven compressor and a method for manufacturing the same.
In a conventional motor-driven compressor, a compression mechanism for compression and discharge of refrigerant gas and an electric motor for driving the compression mechanism are provided in a housing of the compressor. The electric motor is provided in a motor housing that forms a part of the housing. A conductor connected to a motor drive circuit and a lead wire drawn from the electric motor are electrically connected through a connecting terminal in a cluster block that is provided in the motor housing. Japanese Unexamined Patent Application Publication No. 2006-42409 discloses a motor-driven compressor in which such cluster block is mounted to a stator core of the electric motor.
In the compressor disclosed in the publication No. 2006-42409, a projection with a dovetail cross section is formed in the cluster block, and a groove with a dovetail cross section is formed in the outer peripheral surface of the stator core mounted to the inner peripheral surface of the motor housing and extends along the axial direction of the stator core. The projection of the cluster block is slidingly inserted in the groove of the stator core so that the cluster block is mounted to the stator core. The cluster block is connected to a conductor extending through the motor housing.
The stator core with the cluster block and the motor housing are assembled together by shrink fit. In the assembling by shrink fit process, firstly, the motor housing is radially expanded by heating so that the inner diameter of the housing becomes larger than the outer diameter of the stator core, and the stator core with the cluster block is inserted into a suitable position in such heated and expanded motor housing. As the motor housing is cooled, the motor housing is shrunk radially inward and the inner peripheral surface of the motor housing is pressed against the outer peripheral surface of the stator core, so that the stator core is tightly fitted in the motor housing.
In the structure as disclosed in the publication No. 2006-42409, the engagement structure between the cluster block and the stator core allows a little adjustment of the position or orientation of the cluster block, which makes it easy to connect between the cluster block and the conductor. However, when the stator core is inserted into the heated motor housing, the cluster block may be moved and inclined relative to the stator core and then brought into contact with the heated motor housing. This may lead to thermal deformation of the cluster block, which may prevent proper connection between the cluster block and the conductor.
The present invention is directed to providing a motor-driven compressor and a method for manufacturing the same, which prevent the cluster block engaged with the stator core from being moved and inclined into contact with the motor housing when the stator core and the motor housing are assembled by shrink fit.